<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    /* .father{
      width: 400px;
      height: 200px;
      background-color: pink;
      display: flex;
      justify-content:space-between;
      align-items: center;
    }

    .son1,
    .son3{
      width: 100px;
      height: 100px;
      background-color: yellowgreen;
    }
    .son2{
      width: 100px;
      height: 100px;
      background-color: goldenrod;
      flex: 1;
    } */

    .father{
      display: flex;
      height: 100px;
      border: 1px solid #000;
    }
    .son1{
      width: 100px;
      background-color: tomato;
    }
    .son3{
      width: 100px;
      background-color: gold;
    }
    .son2{
      flex: 1;
      background-color: lightblue;
    }
   
  </style>
</head>
<body>
  <div class="father">
    <div class="son1"></div>
    <div class="son2"></div>
    <div class="son3"></div>
  </div>
</body>
</html>